unity – Changing colour of multiple prefab instances when dragging over them


So I am having some issue trying to get it so that when I touch/mousedown that an instantiated prefab changes color and then with mouse down still any other prefab that mouseenters, that prefab should change color as well. the bit of code that i have is shown below. Nothing happens though, other than the one prefab that received the OnMouseDown changes color, but not the others OnMouseEnter. If i remove the if statement though, they do change color OnMouseEnter. Any suggestions on how to do this or what i may be doing wrong?

Thanks

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Letter : MonoBehaviour
{
    Color clkColor = Color.red;

    private bool _clicked;


    void Start()
    {
        _clicked = false;
    }


    void OnMouseDown()
    {
        _clicked = true;
        this.GetComponent<SpriteRenderer>().color = clkColor;
    }

    private void OnMouseEnter()
    {
        if (_clicked == true)
        {
            this.GetComponent<SpriteRenderer>().color = clkColor;
        }

    }
}